New Geoarchaeological Finds in Liang Bawah, the Cave Beneath

Geoarchaeological finds below Liang Bua (Flores, Indonesia): A split-level cave system for Homo floresiensis?

Authors:

Gagan et al

Abstract:

We report on new geoarchaeological finds in a recently discovered cave-chamber (Liang Bawah, “Cave Underneath”) positioned below Liang Bua on the island of Flores, Indonesia, where the type specimen for Homo floresiensis was recovered from Late Pleistocene sediment. At the rear of Liang Bua, a 23-m-long shaft, inclined at 60°, leads to a lower chamber measuring 23 m × 24 m × 5 m high (about half the size of Liang Bua). Stone artefacts and bones were found shallowly buried in rubble at the base of the shaft, and around a 5-m-high mud mound that fills the northwest sector of Liang Bawah. We recovered 17 stone artefacts made from chert and volcanics, and more than 220 well-preserved bone elements belonging to endemic giant rats, pigs, primates, small murid rodents, bats and introduced species. Multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) analysis of uranium and thorium in carbonate coatings on four bones yielded ages of ~ 240–180 ka (endemic giant rat femur), ~ 110–60 ka (unidentified phalanx), ~ 33–23 ka (pig skull fragment), and ~ 7–3 ka (giant rat femur), which overlap with the ~ 95 to 17 ka occupation of Liang Bua by H. floresiensis. The ~ 33–23 ka age of the pig skull fragment indicates that Sus sp. may have dispersed into island Southeast Asia earlier than previously recognised. The passageway at the rear of Liang Bawah, and a currently buried front entrance, represent two possible transport paths for cultural and faunal material to the cave-chamber. Analysis of the geomorphic evolution of Liang Bawah shows that it may have been a Late Pleistocene depocentre for material transported from the occupation chamber of Liang Bua, and a repository for human subsistence refuse, or pit-fall trap, via the rear passage. These physical attributes, and the antiquity of the faunal remains found thus far, indicate that Liang Bawah could contain an archive of the Late Pleistocene and, potentially, remains of H. floresiensis.

Flores Island in Indonesia had Open Savannah in the Early/Middle Pleistocene Quaternary

Avian remains from the Early/Middle Pleistocene of the So'a Basin, central Flores, Indonesia, and their palaeoenvironmental significance

Authors:

Meijer et al

Abstract:

The So'a Basin in central Flores contains the earliest known evidence for hominins on this remote Indonesian island, with stone tools from this region dating back at least 1.0 Ma. At least 16 late Early to early Middle Pleistocene terrestrial fossil localities record evidence for highly insular endemic faunas and proxy evidence for hominins. The hominin presence in the So'a Basin raises many questions as to how, when, and from where hominins arrived on the island, and key issues regarding their adaptation to this insular environment remain poorly understood. Here, we provide palaeoenvironmental data based on avian remains recovered during recent, systematic excavations of late Early to early Middle Pleistocene deposits at Mata Menge and Bo'a Leza in the So'a Basin. At least six species of birds in five avian orders were recovered, forming the oldest bird remains recovered from Wallacea. Two species, a swan (Cygnus sp.) and an eagle owl (Bubo sp.), no longer occur on Flores. The avian assemblage from Mata Menge and Bo'a Leza described here is indicative of an open environment with a strong open, freshwater component and nearby grasslands, and with forests at a distance. In that, it differs from the Late Pleistocene limestone cave site of Liang Bua, the find locality of Homo floresiensis, and is more similar to the Early Pleistocene Homo erectus sites of the Sangiran Dome on Java. Although little is known regarding the identity of the So'a Basin toolmakers, the presence of an open, savannah-type environment in the late Early to early Middle Pleistocene of Flores may have facilitated their dispersal from the Asian shelf into Wallacea.